Influence of the average molecular weight and the concentration of plasticizer on the orientational dynamics of chromophores in guest-host polymers

We report experimental results obtained from dielectric spectroscopy, electro-optic, and second harmonic generation dynamics measurements on different polymers doped with nonlinear optical chromophores. The polymers considered in this work are polyvinylcarbazole plasticized by ethylcarbazole and polystyrenes with different average molecular weights. Altogether the influence of temperature, average molecular weight of the polymer host, and concentration of plasticizer on the orientational processes of chromophores is investigated and described by polymer rheology laws. Finally, these results, which identify the major role played by the average molecular weight of polymers on the orientational dynamics of chromophores, suggest another possible way of optimization for low glass transition temperature photorefractive polymers, where fast orientational response times are required.